JP3536350B2 - Gas cylinder and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

This invention relates to various gas cylinders,
In particular, the present invention relates to a gas cylinder suitable for mounting on an automobile or the like.

[0002]

2. Description of the Related Art In recent years, automobiles using natural gas containing methane as a main fuel have been receiving attention as low-pollution vehicles in the United States and other foreign countries. For such vehicles, C
A gas cylinder called an NG tank (Compressed Natural Gas Tank) is installed.

Such gas cylinders for automobiles have hitherto been known.
It is made of metal such as steel or aluminum alloy, but metal is heavy and reduces fuel consumption. in addition,
The calorific value per unit weight of natural gas is only about half that of gasoline, so if you try to increase the distance that you can run without refueling like a gasoline car, you have to carry about twice as much natural gas as gasoline. This in turn increases gross vehicle weight and reduces fuel economy. Therefore, weight reduction of gas cylinders is being considered as a measure for improving fuel efficiency.

By the way, Japanese Patent Publication No. 5-88665 discloses a gas cylinder in which a plastic inner shell having a gas barrier property is covered with a pressure-resistant outer shell made of FRP (fiber reinforced plastic). This gas cylinder
Since it is essentially made of plastic, it is considerably lighter than metal, and if it is used as a natural gas cylinder for automobiles, it can be expected to improve fuel efficiency. On the other hand, on the other hand, FRP is more brittle than metal, so it bursts instantly when it is impacted by a collision accident or other causes, and the debris injures the human body, or natural gas leaks at once and is explosive. I am afraid that a fire may occur. Also, observing the progress of the destruction of the car body in a collision accident, etc., it is reconfirmed that impact is repeatedly applied to the same part as the destruction progresses, but even if it does not burst at the first impact, it is the same. When a second impact is applied to a part, it bursts easily even with a relatively low impact energy, and as a result, the same situation as when it burst with a single impact is created. As described above, gas cylinders, especially fuel gas cylinders for automobiles, are required not only to be ruptured by a single impact but also to be capable of maintaining pressure resistance performance even after repeated impacts. The prevention of rupture and the maintenance of pressure resistance can be solved by setting a high safety factor. However, doing so increases the weight and increases the FRP.
The weight reduction effect, which is the greatest merit of the reduction, will be impaired, and the manufacturing cost will increase.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of conventional gas cylinders, and in addition to being lightweight, it exhibits excellent pressure resistance against repeated impact and is reliable. To provide a gas cylinder with excellent properties.

Another object of the present invention is to provide a method for manufacturing such a gas cylinder at low cost.

[0007]

In order to achieve the above object, the present invention is, as a first invention, a reinforcing layer made of FRP formed on the body of an inner shell having gas barrier properties. A FRP containing a reinforcing fiber and a resin, which has a pressure-resistant outer shell provided so as to cover it and has a tensile elastic modulus of 40 GPa or more and a tensile breaking strain of 1.5% or more. A gas cylinder characterized in that it is configured.
Further, as a second invention, an inner shell having a gas barrier property
And a pressure-resistant outer shell provided so as to cover the inner shell.
And, the outer shell has a tensile modulus of 40 GPa or more,
Reinforcing fiber and resin having a tensile breaking strain of 1.5% or more
The outer shell is made of gas containing FRP.
Arranged at an angle of -15 ° to 15 ° with respect to the axial direction of the cylinder
Arranged at an angle of 75 ° to 105 ° with a layer of reinforced fibers
Arranged with an angle of -30 ° to -60 ° with a layer of reinforcing fibers
A layer of reinforced fiber Arranged at an angle of 30 ° to 60 °
A gas bon, characterized in that it comprises a layer of reinforcing fibers
To provide Further, as a third invention, a gas barrier
Inner shell with pressure resistance and pressure resistance provided to cover the inner shell
And an outer shell having a tensile modulus of 40.
Reinforcing fiber with tensile breaking strain of 1.5% or more at GPa or more
In addition to being composed of FRP containing fibers and resin,
The reinforcing fiber has a tensile strength of 4.5 GPa or more and a tensile breaking strain.
Is characterized in that it contains carbon fiber yarn having a content of 2% or more.
Providing a gas cylinder that does.

The present invention also provides, as a first method for producing such a gas cylinder, a filament winding method or a tape around an inner shell having a gas barrier property whose outer surface is roughened. Using the winding method,
A method for producing a gas cylinder, comprising forming a pressure-resistant outer shell made of FRP containing a reinforcing fiber and a resin, which has a tensile elastic modulus of 40 GPa or more and a tensile breaking strain of 1.5% or more. To do. As a second method, gas burr
Around the inner shell, which has a
Using the tape method or tape winding method, Tension bullet
The modulus is 40 GPa or more and the tensile strain at break is 1.5% or more.
Out of pressure resistance consisting of FRP containing reinforcing fiber and resin
The shell is formed and the outer shell is placed in the axial direction of the gas cylinder.
Layers of reinforcing fibers arranged at an angle of -15 ° to 15 ° to
And a layer of reinforcing fibers arranged at an angle of 75 ° to 105 °
And a layer of reinforcing fibers arranged at an angle of -30 ° to -60 °
When, A layer of reinforcing fibers arranged at an angle of 30 ° to 60 °
Provided is a method for manufacturing a gas cylinder formed by. further,
As a third method, around the inner shell having gas barrier properties
Filament winding or tape wine
Using the Dying method, If the tensile modulus is 40 GPa or more,
Tensile breaking strain is 1.5% or more.
Form a pressure-resistant outer shell made of FRP and
As a strong fiber, the tensile strength is 4.5 GPa or more, the tensile breaking
For gas cylinders that use carbon fiber yarn with a strain of 2% or more
A manufacturing method is provided.

The present invention will be described in detail based on one embodiment thereof. In FIG. 1, a gas cylinder comprises an inner shell 1 having a gas barrier property and a pressure-resistant outer shell provided so as to cover the inner shell 1. 2 and. This gas cylinder as a whole has a body portion A, an end plate portion B following it, and a nozzle mounting portion 3. A nozzle mounting metal fitting 4 is mounted on the nozzle mounting metal fitting 3, and a nozzle 5 is attached to the nozzle mounting metal fitting 4. Is attached. The nozzle 5 is covered and protected by the cap 6.

In the above, the inner shell has a function of preventing gas leakage. Further, as will be described later, it also acts as a core when forming a pressure resistant outer shell.

The inner shell is made of a metal, for example, a light alloy such as a thin aluminum alloy or a magnesium alloy. Further, it may be made of resin such as polyethylene resin, polypropylene resin, polyamide resin, ABS resin, polybutylene terephthalate resin, polyacetal resin, polycarbonate resin and the like. ABS resin is preferable in terms of excellent impact resistance. Such a resin inner shell can be manufactured by, for example, a well-known blow molding method. Uses a composite blow molding method and has excellent gas sealing properties.
For example, a layer of polyamide resin may have a multi-layer structure in which it is sandwiched by layers of high-density polyethylene resin having excellent rigidity. Further, the inner shell may be made of FRP. Such an FRP inner shell can be manufactured, for example, by injection molding a resin containing reinforcing fibers, which will be described later, including short fibers having a fiber length of about 2 to 10 mm.

The inner shell has a function of preventing gas leakage as described above. In order to improve such action, it is also preferable to form a gas barrier layer on the inner surface and / or the outer surface. For example, when a nitrogen gas containing fluorine is used as a blowing gas during blow molding, a gas barrier layer made of a fluororesin coating can be formed on the inner surface of the inner shell. Alternatively, a gas barrier layer may be formed by forming a plating film of a metal such as copper, nickel or chromium on the outer surface. The metal plating film can be formed by an electrolytic plating method or an electroless plating method. When the inner shell is manufactured by the composite blow molding method, a layer of polyamide resin or the like having an excellent gas barrier property is arranged on the inner side, and a layer of easily plating, for example, ABS resin is arranged on the outer side to form a metal plating film. Can also be facilitated.

The inner shell has an inner surface of 2.5 to 5 cm.
It is possible to provide ring-shaped ribs extending in the circumferential direction at regular intervals. Such an inner shell can be obtained, for example, by making a half-divided inner shell made of a plastic with ribs, and joining and integrating them. These ribs improve the strength of the inner shell, prevent the inner shell from being deformed when the outer shell described later is formed, and reduce the strength of the outer shell due to meandering and uneven distribution of reinforcing fibers, variations in strength, and eventually pressure resistance. Help prevent.

Referring again to FIG. 1, the body portion A of the inner shell is made of FRP which is formed by hoop-winding a reinforcing fiber yarn, which will be described later, or by combining a woven fabric of such a reinforcing fiber yarn and a resin. Reinforcing layer 7 is formed. The reinforcing layer 7 is provided on the end plate portion B.
May extend to a part of. However, in the present invention, it is not essential to have the reinforcing layer.

On the other hand, the outer shell 2 is made of FRP containing a reinforcing fiber and a resin having a tensile elastic modulus of 40 GPa or more and a tensile breaking strain of 1.5% or more. Tensile elastic modulus is 40 GP
By configuring the outer shell with FRP having a tensile breaking strain of 1.5% or more, the gas cylinder exhibits excellent pressure resistance against repeated impact and is also highly reliable. .

That is, in order to improve the impact energy absorption performance of the outer shell, the tensile elastic modulus (E) and the fracture strain (ε) of the outer shell are increased, that is, the equation: W = (1/2) × It suffices to increase the fracture strain energy W defined by E × ε ² , but in consideration of weight reduction as well, it is necessary that the tensile elastic modulus is at least 40 GPa. If it is less than 40 GPa, the amount of deformation when shocked becomes too large,
There is a concern that the inner shell may be damaged and gas may leak. Also, it becomes weak against repeated impact. On the other hand, the tensile breaking strain needs to be at least 1.5% in order to increase the breaking strain energy in the above equation. If it is less than 1.5%, the damage and breakage of the reinforcing fiber will be remarkable when an impact is applied, and when the impact is repeatedly applied, even if the damage due to the first impact is slight, further impact is applied to the same part. There are concerns about gas leaks and bursts. Such an outer shell can be constructed as follows, for example.

That is, the above-mentioned inner shell can be constructed by forming a wound layer of a reinforcing fiber yarn containing a resin around the inner shell as a so-called mandrel by a well-known filament winding method or tape winding method, and molding the wound layer. . At this time, when there is a reinforcing layer, the average height of the outer surface of the inner shell including the surface is 10 to 20.
It is preferable to form a rough surface of about 0 μm because slippage of the reinforcing fiber yarn at the time of winding can be prevented and disturbance of distribution of the reinforcing fiber can be reduced.

As the reinforcing fiber yarn, at least one kind of high-strength and high-modulus fiber yarn such as carbon fiber yarn, glass fiber yarn, and organic high elastic modulus fiber yarn (for example, polyaramid fiber) can be used. It is preferable that these reinforcing fiber yarns are non-twisted fiber yarns having excellent openability in the sense that stress concentration due to bending can be reduced and generation of voids can be reduced. And, even among such reinforcing fiber yarns, it has excellent specific strength and specific elastic modulus, there is almost no occurrence of yarn breakage or fluff during winding, and not only the improvement of productivity but also the strength due to mixing of yarn seams and fluff. A carbon fiber yarn having a tensile strength of 4.5 GPa or more and a tensile breaking strain of 2% or more, which can prevent deterioration of properties and impact resistance, is preferable.

As the resin, thermosetting resins such as epoxy resin, unsaturated polyester resin, vinyl ester resin and phenol resin, polyamide resin, polyethylene terephthalate resin, ABS resin, polyetherketone resin, polyphenylene sulfide resin, Poly-4-
A thermoplastic resin such as methylpentene-1 resin or polypropylene resin can be used. In particular, in order to increase the impact absorption energy due to deformation, it is preferable to select and use a resin having a large tensile breaking strain, preferably a resin having a tensile breaking strain of 3% or more.

By the way, the ratio of the tensile tension in the axial direction of the gas cylinder generated by the internal pressure and the tensile tension in the circumferential direction is approximately 1: 2. Therefore, we aim to improve the pressure resistance by increasing the strength and tensile modulus as well as reducing the weight.
In addition, in order to improve the in-plane isotropy and enhance the impact resistance, it is necessary that the above-mentioned tensile strength is 4.5 GPa or more and tensile breaking strain is 2% or more, especially regarding the arrangement of the reinforcing fibers. When using different carbon fiber yarns, a layer of reinforcing fibers arranged in order from the inside at an angle of -15 ° to 15 °, preferably -5 ° to 5 ° with respect to the axial direction of the gas cylinder,
Layers of reinforcing fibers arranged at an angle of 5 ° to 105 °, preferably 85 ° to 100 °, and reinforcing fibers arranged at an angle of -30 ° to -60 °, preferably -40 ° to -50 °. And a layer of reinforcing fibers arranged at an angle of 30 ° to 60 °, preferably 40 ° to 50 °, and-
A layer of reinforcing fibers arranged at an angle of 15 ° to -15 °;
A layer of reinforcing fibers arranged at an angle of 5 ° to 105 °, -3
A layer of reinforcing fibers arranged at an angle of 0 ° to -60 °, 30
The volume ratio of the amount of reinforcing fibers to the layer of reinforcing fibers arranged at an angle of 60 ° to 60 ° is 1: 1.5 to 2.5: 0.2 to 1.2:
It is preferable to set it in the range of 0.2 to 1.2. Mainly -1
The layers of 5 ° to 15 ° and 75 to 105 ° have a pressure resistance of -3.
The 0 ° to -60 ° and 30 ° to 60 ° layers have impact resistance
Each works to improve. That is, in order to increase the residual strength after receiving an impact, -30 ° to
The -60 ° layer and the 30 ° -60 ° layer are preferably on the outside. Since the bending stress due to the internal pressure acts on the boundary portion between the body portion and the end plate portion, it is preferable to make it a little thicker. Further, by interposing the above-mentioned mat of reinforcing fibers or the FRP layer of the non-woven fabric and the resin between the layers, or by forming a similar FRP layer as the outermost layer, the impact energy can be dispersed. The impact resistance will be further improved. Similarly, the outermost layer can be formed as an FRP layer of resin having excellent impact resistance of glass fiber or organic fiber and resin, or as a resin layer of polyethylene resin, polyamide resin, urethane resin or the like.

[0021]

[Examples and Comparative Examples]

Example Inner shell made of blow-molded high-density polyethylene resin (outer diameter: 200 mm, total length excluding nozzle mounting part: 1.00
An outer shell was formed by a filament winding method on the inner shell of the so-called mandrel (0 mm, wall thickness: 2 mm). For filament winding, carbon fiber yarn (single yarn diameter: 7 μm, number of single yarn: 12,000, tensile strength: 4.8 GPa, tensile breaking strain: 2.1) impregnated with epoxy resin (tensile breaking strain: 4%). %) With respect to the cylinder axial direction in the order of 3 ° layer, 88 ° layer, -45 layer.
To form a 45 ° layer and a 3 ° layer, 88 °
The carbon layers are wound so that the volume ratio of the carbon fibers in the 45 ° layer, the −45 ° layer and the 45 ° layer is 1: 2: 0.9: 0.9, and heated in an oven at 130 ° C. for 2 hours to remove the gas cylinder. The body was molded. The tensile modulus of elasticity of the outer shell thus obtained is 44 GPa,
The tensile strain at break was 2.0%, and the outer diameter of the main body was 216 mm.

Next, a tap nose having a radius of curvature of 8 mm and a weight of 2 kg was made to collide with the center of the main body 50 times at a speed of 2 m / sec by using a falling weight tester. The damaged area as seen with an ultrasonic flaw detector (projected area as seen from the vertical direction) was 0.1 cm ² . In addition, the ratio of pressure resistance before and after collision in a pressure test using water as a pressure source was 1.00, and no reduction in pressure resistance performance due to repeated impact was observed.

Comparative Example 1 A carbon fiber yarn was prepared by using a single yarn diameter: 7 μm and a single yarn number: 12,000.
A main body was obtained in the same manner as in Example except that the tensile strength was 3.0 GPa and the tensile strain at break was 1.3%. The tensile elastic modulus of the outer shell was 43 GPa and the tensile strain at break was 1.2%.

When this main body was tested in the same manner as in the example, the damaged area was 7.2 cm ² , and the pressure resistance ratio before and after the collision was 0.55.

Comparative Example 2 A carbon fiber yarn was prepared by using a single yarn diameter: 7 μm and a single yarn number: 12,000.
A main body was obtained in the same manner as in the example except that the tensile strength was 1.4 GPa and the tensile strain at break was 1.6%. The tensile elastic modulus of the outer shell was 35 GPa and the tensile strain at break was 1.6%.

When this main body was tested in the same manner as in the example, the damaged area was 6.5 cm ² , and the pressure resistance ratio before and after the collision was 0.62.

[0027]

The gas cylinder of the present invention is a FRP containing a reinforcing fiber and a resin, which has a tensile elastic modulus of 40 GPa or more and a tensile breaking strain of 1.5% or more so as to cover an inner shell having a gas barrier property. Since the outer shell made of the material is provided, as is clear from the comparison between the example and the comparative example, it exhibits excellent pressure resistance against repeated impact and has excellent reliability. Also, since it is essentially made of plastic, it is of course lightweight. Therefore, the gas cylinder of the present invention is particularly suitable as a CNG tank for automobiles, which is required to be lightweight and particularly excellent in reliability.

In the present invention, the above-mentioned gas cylinder is provided around the inner shell having a gas barrier property by using the filament winding method or the tape winding method, and the tensile elastic modulus is 40 GPa or more and the tensile breaking strain is 1. Since it is produced by forming a pressure resistant outer shell made of FRP containing 5% or more of reinforcing fibers and resin, it can be produced at low cost.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a gas cylinder according to an embodiment of the present invention.

[Explanation of symbols]

1: Inner shell 2: Outer shell 3: Nozzle mounting part 4: Nozzle mounting bracket 5: Nozzle 6: Cap 7: Reinforcing layer A: trunk B: End plate

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-89098 (JP, A) JP-A-3-113199 (JP, A) JP-A-58-219933 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B29D 22/00 F17C 1/16

Claims (10)

(57) [Claims] 1. A FRP on the body of an inner shell having gas barrier properties.
And a pressure-resistant outer shell provided so as to cover the inner shell, and the outer shell has a tensile elastic modulus of 4
A gas cylinder characterized by being composed of FRP containing a reinforcing fiber and a resin, which has a tensile breaking strain of 1.5% or more at 0 GPa or more. 2. The gas cylinder according to claim 1, wherein the inner shell is made of metal, resin or FRP. 3. The gas cylinder according to claim 1, wherein a gas barrier layer is formed on the inner surface and / or the outer surface of the inner shell. 4. An inner shell having a gas barrier property and a pressure resistant outer shell provided so as to cover the inner shell, wherein the outer shell has a tensile elastic modulus of 40 GPa or more and a tensile breaking strain. Is 1.
5% or more, with is composed of FRP comprising reinforcing fibers and a resin, the outer shell, a layer of reinforcing fibers arranged at an angle of -15 ° to 15 ° to the axial direction of the gas cylinder , A layer of reinforcing fibers arranged at an angle of 75 ° to 105 °, a layer of reinforcing fibers arranged at an angle of −30 ° to −60 °, and a reinforcing fiber arranged at an angle of 30 ° to 60 ° And a gas cylinder containing a layer of. 5. A temperature range of -15 ° to 1 with respect to the axial direction of the gas cylinder.
A layer of reinforcing fibers arranged at an angle of 5 °, 75 ° -105
A layer of reinforcing fibers arranged at an angle of −30 ° to −60
Layer of reinforcing fibers arranged at an angle of 30 ° to 30 °
The volume ratio of the amount of reinforcing fibers to the layer of reinforcing fibers arranged at an angle of 1: 1.5-2.5: 0.2-1.2: 0.2-1.2
The gas cylinder according to claim 4 , which is in the range of. 6. An inner shell having a gas barrier property and a pressure resistant outer shell provided so as to cover the inner shell, wherein the outer shell has a tensile elastic modulus of 40 GPa or more and a tensile breaking strain. Is 1.
5% or more, with is composed of FRP comprising reinforcing fibers and a resin, said reinforcing fiber has a tensile strength of 4.5
A gas cylinder comprising a carbon fiber yarn having a tensile breaking strain of 2% or more at GPa or more. 7. A filament winding method or a tape winding method is used to form a tensile elastic modulus of 4 around an inner shell having a gas barrier property whose outer surface is roughened.
A method for producing a gas cylinder, which comprises forming a pressure-resistant outer shell made of FRP containing a reinforcing fiber and a resin and having a tensile breaking strain of 1.5% or more at 0 GPa or more. 8. A filter is provided around the inner shell having gas barrier properties.
Lamente winding or tape winding
Using the method Tensile elastic modulus of 40 GPa or more, tensile breaking strain
Containing reinforcing fiber and resin having a content of 1.5% or more
And a reinforcing fiber layer arranged at an angle of −15 ° to 15 ° with respect to the axial direction of the gas cylinder and an angle of 75 ° to 105 °. a layer of reinforcing fibers, the reinforcing fibers arranged at an angle of -30 ° to 60 ° layer and, formed to the Ruga Subonbe in a layer of reinforcing fibers arranged at an angle of 30 ° to 60 ° Production method. 9. -15 ° to 1 with respect to the axial direction of the gas cylinder
A layer of reinforcing fibers arranged at an angle of 5 °, 75 ° -105
A layer of reinforcing fibers arranged at an angle of −30 ° to −60
Layer of reinforcing fibers arranged at an angle of 30 ° to 30 °
The volume ratio of the amount of reinforcing fibers to the layer of reinforcing fibers arranged at an angle of 1: 1.5-2.5: 0.2-1.2: 0.2-1.2
9. The method for manufacturing a gas cylinder according to claim 8 , wherein 10. A space around an inner shell having a gas barrier property.
Filament winding method or tape winding method
Using the method Tensile rupture when the tensile modulus is 40 GPa or more
FR containing reinforcing fiber and resin with strain of 1.5% or more
It forms a pressure-resistant outer shell made of P and has a tensile strength of 4.5 GPa or more and a tensile breaking strain of 2 as reinforcing fibers.
Ruga Subonbe manufacturing method of use of% or more in the carbon fiber yarns is.